TREATMENT OF ANTIREFLECTION AN TIN OXIDE-COATED ANODIZED ALUMINUM SELECTIVE ABSORBER SURFACE

Nickel-pigmented anodic aluminum oxide, Ni-Al2O3 was pyrolytically coa ted with tin oxide (SnO2). The undesirable increase of reflectance in the solar spectrum due to the high refractive index of the SnO2 film w as compensated by an antireflection layer. The layer was applied by a simple dipping technique in a bath containing a commercial colloidal s ilica sol which forms a silica (SiO2) layer. The infrared reflectance is nearly unaffected by the silica sol treatment process. Preliminary test results indicate that treated samples are resistant to temperatur es as high as 300 degrees C as well as to corrosion in an 8% sulfuric acid solution. In addition, the optical properties were unaffected by outdoor exposure for two months. (C) 1998 Published by Elsevier Scienc e B.V. All rights reserved.